Japan's technology is an entire generation ahead of America's and America has no way of retaliating against a country with ICBMs, surface to air and air to air missiles, anti-ship missiles, and supersonic jets and a willingness to escalate to armageddon over a shrimp boat.
Japan reduces America, Britain, and Germany to wastelands and plants its boot firmly on the throat of the world as the sole superpower and the Earth descends into the eternal hell of the Empire of the Rising Sun for decades to come before the sole hope of internal revolution can manifest to save the planet from its new hegemon.
America's nuclear retaliation is entirely ineffectual; being reliant on slow and easily intercepted bombers that have no hope of surviving the trip to any major Japanese sites while the Empire quickly comes to dominate the skies and its navy more or less deletes the British and American pacific fleets while the USA and UK are ground into the dirt for decades to come, with the survivors likely seeing their countries be turned into miserable extractive de-facto colonies while their remaining industry is largely dismantled to eliminate the possibility of competing with the Zaibatsu.
What will follow will be a very dark period in history for the world as the entirety of it is swallowed into Japan's imperialisation economy with only countries Japan essentially allows to develop industry having any that's not almost exclusively geared towards enriching the Home Islands. The immiseration around the world will be cataclysmic and enormous numbers of people will die as they always do when an empire of this sort of scale consolidates and enforces its extractionist order and takes a look at which parts of the world it'd like to turn into outright settler colonies.